PTC Software Developer Interview Questions and Answers

Round duration - 45 minutes
Round difficulty - Medium

Technical Interview round with questions on DSA.

Q1. 
Reverse Words in a String: Problem Statement
You are given a string of length N. Your task is to reverse the string word by word. The input may contain multiple spaces between words and may have leading o...read more
Ans. 
Reverse words in a string while handling leading, trailing, and multiple spaces.
• Split the input string by spaces to get individual words

• Reverse the order of the words

• Join the reversed words with a single space in between

• Handle leading, trailing, and multiple spaces appropriately
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Q2. 
Reverse a Stack Using Recursion
You are given a stack of integers. Your task is to reverse the stack using recursion without using any extra space other than the internal stack space used due to recursion...read more
Ans. 
Reverse a stack using recursion without using any extra space other than the internal stack space.
• Use recursion to pop all elements from the original stack and store them in function call stack.

• Once the stack is empty, push the elements back in reverse order.

• Base case of recursion should be when the original stack is empty.
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Round duration - 45 minutes
Round difficulty - Medium

Technical Interview round with questions on DSA.

Q1. 
Convert a Binary Tree to its Mirror Tree
Given a binary tree, convert this binary tree into its mirror tree. A binary tree is a tree in which each parent node has at most two children. The mirror of a bin...read more
Ans. 
Convert a binary tree to its mirror tree by interchanging left and right children of all non-leaf nodes.
• Traverse the binary tree in a recursive manner.

• Swap the left and right children of each non-leaf node.

• Continue this process until all nodes have been processed.
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Q2. 
Remove Nth Node from End of Linked List
You are given a singly linked list with 'N' nodes, each containing integer data, and an integer 'K'. Your goal is to remove the 'K'th node counting from the end of ...read more
Ans. 
Remove the Kth node from the end of a singly linked list.
• Use two pointers approach to find the Kth node from the end.

• Handle edge cases like removing the head node or removing the last node.

• Update the pointers to remove the Kth node and reconnect the list.
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Round duration - 30 minutes
Round difficulty - Easy

Typical Managerial round.

Round duration - 60 minutes
Round difficulty - Easy

Technical Interview round with questions based on DSA, OOPS and puzzles.

Q1. 
Reverse Linked List Problem Statement
Given a Singly Linked List of integers, your task is to reverse the Linked List by altering the links between the nodes.
Input:
The first line of input is an intege...read more
Ans. 
Reverse a singly linked list by altering the links between nodes.
• Iterate through the linked list and reverse the links between nodes

• Use three pointers to keep track of the current, previous, and next nodes

• Update the links between nodes until the end of the list is reached
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Q2. 
Reverse Number Problem Statement
Ninja is exploring new challenges and desires to reverse a given number. Your task is to assist Ninja in reversing the number provided.
Note:
If a number has trailing ze...read more
Ans. 
Implement a function to reverse a given number, omitting trailing zeros.
• Create a function that takes an integer as input and reverses it while omitting trailing zeros

• Use modulo and division operations to extract digits and reverse the number

• Handle cases where the reversed number has leading zeros by omitting them

• Ensure the reversed number is within the constraints specified
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Q3. 
Reverse the String Problem Statement
You are given a string STR which contains alphabets, numbers, and special characters. Your task is to reverse the string.
Example:
Input:
STR = "abcde"
Output:
"e...read more
Ans. 
Reverse a given string containing alphabets, numbers, and special characters.
• Iterate through the string from end to start and append each character to a new string.

• Use built-in functions like reverse() or slicing to reverse the string.

• Handle special characters and numbers while reversing the string.

• Ensure to consider the constraints provided in the problem statement.
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Q4. What is overloading in the context of Object-Oriented Programming (OOP)?
Ans. 
Overloading in OOP is the ability to define multiple methods with the same name but different parameters.
• Overloading allows multiple methods with the same name but different parameters to coexist in a class.

• The compiler determines which method to call based on the number and type of arguments passed.

• Example: having multiple constructors in a class with different parameter lists.
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Round duration - 60 minutes
Round difficulty - Medium

Technical round with question based on Web Dev, Cloud Computing, Networking etc.

Q1. What is TELNET?
Ans. 
TELNET is a network protocol used to establish a connection with a remote computer over a network.
• TELNET stands for Telecommunication Network.

• It allows a user to log in to a remote computer and execute commands as if they were directly connected to that computer.

• TELNET operates on port 23.

• It is not secure as the data is transmitted in plain text.

• SSH (Secure Shell) is a more secure alternative to TELNET.
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Q2. What is the difference between TELNET and SSH?
Ans. 
TELNET is insecure, while SSH is secure for remote access to servers.
• TELNET sends data in plain text, while SSH encrypts data for secure communication

• SSH uses public-key cryptography for authentication, TELNET does not

• SSH provides secure remote access to servers, TELNET does not prioritize security

• TELNET operates on port 23, while SSH operates on port 22
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Q3. 
Problem: Sort an Array of 0s, 1s, and 2s
Given an array/list ARR consisting of integers where each element is either 0, 1, or 2, your task is to sort this array in increasing order.
Input:
The input sta...read more
Ans. 
Sort an array of 0s, 1s, and 2s in increasing order.
• Use a three-pointer approach to partition the array into sections of 0s, 1s, and 2s.

• Iterate through the array and swap elements based on their values.

• Time complexity should be O(n) to meet the constraints.
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Q4. What is a hypervisor?
Ans. 
A hypervisor is a software that creates and runs virtual machines on a physical host machine.
• Hypervisors allow multiple operating systems to run on a single physical machine

• They provide isolation between virtual machines

• Examples include VMware ESXi, Microsoft Hyper-V, and KVM
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Q5. Can you explain cloud computing in layman’s terms?
Ans. 
Cloud computing is like renting a computer over the internet instead of owning one.
• Cloud computing allows users to access and store data and applications over the internet instead of on their own physical computer.

• It offers scalability, flexibility, and cost-effectiveness as users can easily adjust their storage and computing needs.

• Examples include services like Amazon Web Services (AWS), Microsoft Azure, and Google Cl...read more
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Q6. What are the stages in the Software Development Life Cycle?
Ans. 
The stages in the Software Development Life Cycle include planning, design, development, testing, deployment, and maintenance.
• 1. Planning: Define project scope, requirements, and timelines.

• 2. Design: Create architecture, UI/UX, and database design.

• 3. Development: Write code based on design specifications.

• 4. Testing: Verify functionality, performance, and security.

• 5. Deployment: Release the software to users or clients.

• ...read more
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Round duration - 60 minutes
Round difficulty - Medium

Technical Interview round with questions based on DSA and OOPS. A detailed discussion on my projects was also carried out.

Q1. 
Common Elements in Three Sorted Arrays
Given three sorted arrays A, B, and C of lengths N, M, and K respectively, your task is to find all elements that are present in all three arrays.
Input:
The first...read more
Ans. 
Find common elements in three sorted arrays and output them in order.
• Iterate through all three arrays simultaneously using three pointers.

• Compare elements at pointers and move pointers accordingly.

• If elements are equal, add to result and move all pointers forward.

• If elements are not equal, move pointer of smallest element forward.
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Q2. What is a volatile variable?
Ans. 
A volatile variable is a variable that can be modified by multiple threads simultaneously.
• Volatile variables are used in multithreading to ensure visibility of changes made by one thread to other threads.

• They are not cached in thread's local memory, but always read from main memory.

• They are typically used for flags or status variables that are accessed by multiple threads.

• Example: 'volatile boolean flag = true;'
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Q3. Can you explain the concept of multithreading in Java?
Ans. 
Multithreading in Java allows multiple threads to execute concurrently, improving performance and responsiveness.
• Multithreading allows multiple threads to run concurrently within a single process.

• Threads share the same memory space, allowing for efficient communication and data sharing.

• Java provides built-in support for multithreading through the Thread class and Runnable interface.

• Example: Creating a new thread using ...read more
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Round duration - 30 minutes
Round difficulty - Easy

HR round with typical behavioral problems.

Round duration - 60 minutes
Round difficulty - Easy

Need to write working code on a shared document so that the interviewer can see if you can put your ideas into code. In this round, they are not bothered about time complexity of your algorithm. They just wanted to know if you can code whatever you think. So if you do not find best solution also it is OK but write the code for average case at-least.

Q1. 
Problem: Search In Rotated Sorted Array
Given a sorted array that has been rotated clockwise by an unknown amount, you need to answer Q queries. Each query is represented by an integer Q[i], and you must ...read more
Ans. 
Search for integers in a rotated sorted array efficiently.
• Use binary search to find the pivot point where the array is rotated.

• Based on the pivot point, apply binary search on the appropriate half of the array.

• Return the index of the integer if found, else return -1.

• Time complexity should be O(logN) for each query.
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Q2. 
Pair Sum in Binary Search Tree
Given a Binary Search Tree (BST) and a target value 'K', determine if there exist two unique elements in the BST such that their sum equals the target 'K'.
Explanation:
A ...read more
Ans. 
Check if there exist two unique elements in a BST that sum up to a target value 'K'.
• Traverse the BST in-order to get a sorted array of elements.

• Use two pointers approach to find the pair sum in the sorted array.

• Consider edge cases like duplicate elements or negative values.

• Time complexity can be optimized to O(n) using a HashSet to store visited nodes.
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Round duration - 60 minutes
Round difficulty - Medium

I was interviewed for vcloud team so they asked me questions on Cloud, DSA etc.

Q1. 
Reverse List In K Groups Problem Statement
You are provided with a linked list having 'N' nodes and an integer 'K'. Your task is to reverse the linked list in groups of size K. If the list is numbered fro...read more
Ans. 
Reverse a linked list in groups of size K
• Iterate through the linked list in groups of size K

• Reverse each group of nodes

• Handle cases where the last group may have fewer than K nodes
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Q2. 
Reverse Stack with Recursion
Reverse a given stack of integers using recursion. You must accomplish this without utilizing extra space beyond the internal stack space used by recursion. Additionally, you ...read more
Ans. 
Reverse a given stack of integers using recursion without using extra space or loops.
• Use recursion to pop all elements from the original stack and store them in function call stack

• Once the stack is empty, push the elements back in reverse order using recursion

• Use the top(), pop(), and push() methods to manipulate the stack
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Q3. What is cloud computing?
Ans. 
Cloud computing is the delivery of computing services over the internet, including storage, databases, networking, software, and more.
• Cloud computing allows users to access resources on-demand without the need for physical infrastructure.

• Examples of cloud computing services include Amazon Web Services (AWS), Microsoft Azure, and Google Cloud Platform.

• Cloud computing offers scalability, flexibility, cost-effectiveness, ...read more
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Q4. What are the benefits of cloud computing?
Ans. 
Cloud computing offers scalability, cost-efficiency, flexibility, and improved collaboration.
• Scalability: Easily scale resources up or down based on demand without the need for physical infrastructure.

• Cost-efficiency: Pay only for the resources you use, reducing upfront costs and maintenance expenses.

• Flexibility: Access data and applications from anywhere with an internet connection, enabling remote work and collaborat...read more
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Q5. What are the challenges of cloud computing?
Ans. 
Challenges of cloud computing include security concerns, data privacy issues, and potential downtime.
• Security concerns: Data breaches and unauthorized access are major risks in cloud computing.

• Data privacy issues: Ensuring compliance with regulations like GDPR can be challenging when data is stored in the cloud.

• Potential downtime: Dependence on internet connectivity and cloud service providers can lead to downtime affe...read more
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